<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			*{
				margin: 0;
				padding: 0;
			}
			div{
				width: 100px;
				height: 100px;
				
			}
			.box1{
				background: red;
			}
			.box2{
				background: green;
				position: absolute;
				/* left: 0; */
				right: 0;
				top: 0;
				
			}
			.box3{
				background: blue;
			}
				
			span{
				width: 100px;
				height: 100px;
				background: yellow;
				position: absolute;
			}
		</style>
	</head>
	<body>
		<!-- 
			1.什么是绝对定位?
			绝对定位就是相对于body来定位(没有参考点时)
			position: absolute;
			
			
			2.绝对定位注意点
			2.1绝对定位的元素是脱离标准流的
			2.2绝对定位的元素是不区分块级元素/行内元素/行内块级元素
			
			
		 
		 
		 -->
		 
		 <div class="box1"></div>
		 <div class="box2"></div>
		 <div class="box3"></div>
		 <span>我是span</span>
	</body>
</html>
